DRIVING EAST ON ARDSLEY RD. IN SCARSDALE NY, MY VEHICLE ACCELERATED BY ITSELF. AT THE TIME I WAS STARTING TO GO DOWNHILL, CURVING RIGHT WITH A "JERSEY BARRIER" IN THE CENTER OF THE ROADWAY. I TRIED TO GO AROUND THE VEHICLE DIRECTLY IN FRONT OF ME BUT MY RIGHT REAR SIDESWIPED HIS LEFT REAR. IT CONTINUED TO ACCELERATE AROUND A RIGHT CURVE (DOWNHILL). I COULD NOT STOP. I STRUCK AN S.U.V. JUST STARTING TO MOVE WITH TRAFFIC. THE VEHICLE I SIDESWIPED SUSTAINED NO DAMAGE. BOTH THE VEHICLE I STRUCK AND MY VEHICLE WERE HEAVILY DAMAGED (MY AUTO IS $4500). BOTH VEHICLES TOWED FROM THE SCENE. GREENBURGH (NY) POLICE RESPONDED. NO INJURIES AS OF THIS TIME. I REPORTED THIS TO THE 800 NUMBER OF SUBARU. THEY TOOK ALL THE INFORMATION OVER THE PHONE. I HAVE NOT HEARD FROM THEM. I TOLD THEM I WAS REPORTING THIS BECAUSE I DIDN'T KNOW IF ANYONE ELSE EXPERIENCED THE SAME FRIGHT. THE TIME WAS 4:50PM. *TR